1. Field Of The Invention
This invention relates to gravel packers, and more particularly, to a retrievable gravel packer set without rotation and to a retrieving tool therefor.
2. Description Of The Prior Art
When gravel packing a well it is desirable to minimize the number of trips downhole to operate or install tools and perform the gravel packing operation. One ideal method would be to make one trip downhole to set a sump or false bottom packer, then make one more run to set a gravel packer, perform a gravel packing operation, and remove the tool string and operating tool out of the well, leaving the gravel packer ready for production. Another desirable feature would be to enable gravel packing multiple zones within the well bore. Also, in deviated wells or in situations where the packer is set on bottom, it is desirable that the gravel packing operation be carried out without rotation of the tool string. Further, it is desirable to be able to retrieve the gravel packer when desired, or at least be able to mill the packer out of the well bore.
One retrievable gravel packer which meets these characteristics is disclosed in U.S. Pat. No. 4,664,188 to Zunkel et al., assigned to the assignee of the present invention. The packer in this patent has an inner mandrel with an expandable packing means thereon and a slip assembly positioned below the packing means. A setting tool engages a threaded portion in the mandrel and applies a downward force on an upper shoe means for compressing the packing means for sealing engagement with the well bore and for setting the slip means into gripping engagement with the well bore. Locking means such as a plurality of individual locking dogs grippingly engage an outer surface of the mandrel for preventing relative upper movement of the upper shoe means. A releasing means is provided for releasing the mandrel when desired so that the packing means and slips are disengaged for retrieval of the gravel packer.
The gravel packer of the present invention includes a ratchet means for preventing upward movement of a pusher sleeve with respect to a mandrel and has relatively thin wall thicknesses which makes it well adapted for use in relatively small well bores while still allowing adequate flow therethrough. Also, the gravel packer of the present inveniion includes port means which allows flow through an upper portion thereof when circulation operations are being carried out by an operating tool.
In the above-referenced patent to Zunkel et al., a retrieving tool is disclosed having an upper collet for engaging the threaded portion of the mandrel in the packer and a spring biased lower mandrel for engaging the releasing piston. The retrieving tool of the present invention comprises upper collet means slidably disposed on a collet support means which is further slidable with respect to a mandrel. This insures proper alignment of the upper mandrel collet means with the threaded portion in the mandrel means. The retrieving tool of the present invention also has a lower mandrel means which is not spring biased, but is free to slide on a lower portion of the mandrel means. This lower collet means may be engaged with a releasing mandrel and locked therewith for releasing and retrieving the packer.
Further, by additional manipulation of the mandrel means in the retrieving tool, the lower collet means may be disengaged from the releasing piston in the event that the packer becomes jammed. In this way, the retrieving tool may still be removed from the packer, and then the packer may be milled out of the well bore because the packer includes anti-rotation means for its components.